Life as a Physicist

Ok. This post is for all my non-physics friends who have been asking me… What just happened? Why is everyone talking about this Higgs thing!?

It does what!?

Actually, two things. It gives fundamental particles mass. Not much help, eh? Fundamental particles are, well, fundamental – the most basic things in nature. We are made out of arms & legs and a few other bits. Arms & legs and everything else are made out of cells. Cells are made out of molecules. Molecules are made out of atoms. Note we’ve not reached anything fundamental yet – we can keep peeling back the layers of the onion and peer inside. Inside the atom are electrons in a cloud around the nucleus. Yes! We’ve got a first fundamental particle: the electron! Everything we’ve done up to now says it stops with the electron. There is nothing inside it. It is a fundamental particle.

We aren’t done with the nucleus yet, however. Pop that open and you’ll find protons and neutrons. Not even those guys are fundamental, however – inside each of them you’ll find quarks – about 3 of them. Two “up” quarks and a “down” quark in the case of the proton and one “up” quark and two “down” quarks in the case of the neutron. Those quarks are fundamental particles.

The Higgs interacts with the electron and the quarks and gives them mass. You could say it “generates” the mass. I’m tempted to say that without the Higgs those fundamental particles wouldn’t have mass. So, there you have it. This is one of its roles. Without this Higgs, we would not understand at all how electrons and quarks have mass, and we wouldn’t understand how to correctly calculate the mass of an atom!

Now, any physicist who has made it this far is cringing with my last statement – as a quick reading of it implies that all the mass of an atom comes from the Higgs. It turns out that we know of several different ways that mass can be “generated” – and the Higgs is just one of them. It also happens to be the only one that, up until July 4th, we didn’t have any direct proof for. An atom, a proton, etc., has contributions from more than just the Higgs – indeed, most of a proton’s mass (and hence, an atom’s mass) comes from another mechanism. But this is a technical aside. And by reading this you know more than many reporters who are talking about the story!

The Higgs plays a second role. This is a little harder to explain, and I don’t see it discussed much in the press. And, to us physicists, this feels like the really important thing. “Electro-Weak Symmetry Breaking”. Oh yeah! It comes down to this: we want to tell a coherent, unified, story from the time of the big-bang to now. The thing about the big-bang is that was *really* hot. So hot, in fact, that the rules of physics that we see directly around us don’t seem to apply. Everything was symmetric back then – it all looked the same. We have quarks and electrons now, which gives us matter – but then it was so hot that they didn’t really exist – rather, we think, some single type of particle existed. Now, and the universe cooled down from the big bang, making its way towards present day, new particles froze out – perhaps the quarks froze out first, and then the electrons, etc. Let me see how far I can push this analogy… when water freezes, it does so into ice crystals. Say that an electron was one particular shape of ice crystal and a quark was a different shape. So you go from a liquid state where everything looks the same – heck – it is just water, to a solid state where the ice crystals have some set of shapes – and by their shape they become electrons or quarks.

Ok, big deal. It seems like the present day “froze” out of the Big Bang. Well, think about it. If our current particles evolved out of some previous state, then we had sure as hell be able to describe that freezing process. Even better – we had better be able to describe that original liquid – the Big Bang. In fact, you could argue, and we definitely do, that the rules that governed physics at the big bang would have to evolve to describe the rules that describe our present day particles. They should be connected. Unified!! Ha! See how I slipped that word in up above!?

We know about four forces in the universe: the strong (holds a proton together), weak (radioactive decay is an example), electro-magnetism (cell phones, etc. are examples), and gravity. The Higgs is a key player in the unification of the weak force and the electro-magnetic force. Finding it means we actually have a bead on how nature unifies those two forces. That is HUGE! This is a big step along the way to putting all the forces back together. We still have a lot of work to do!

Another technical aside. We think of the first role – giving fundamental particles mass – a consequence of the second – they are not independent roles. The Higgs is key to the unification and in order to be that key, it must also be the source of the fundamental particle’s mass.

How long have you been searching for it?

A loooooong time. We are like archeologists. Nature is what nature is. Our job is to figure out how nature works. We have a mathematical model (called the Standard Model). We change it every time we find an experimental result that doesn’t agree with the calculation. The last time that happened was when we stumble upon the unexpected fact that neutrino’s have mass. The time before that was the addition of the Higgs, and that modification was first proposed in 1964 (it took a few years to become generally accepted). So, I suppose you could say in some sense we’ve been looking for it since 1964!

It isn’t until recently, however (say in the late 90’s) that the machines we use have become powerful enough that we could honestly say we were “in the hunt for the Higgs.” The LHC, actually, had finding the Higgs as one of its major physics goals. There was no guarantee – no reason nature had to work like that – so when we built it we were all a little nervous and excited… ok. a lot nervous and excited.

So, why did it take so long!? The main reason is we hardly ever make it in our accelerators! It is very very massive!! So it is very hard to make. Even at the LHC we make one every 3 hours… The LHC works by colliding protons together at a very high speed (almost the speed of light). We do that more than 1,000,000 times a second… and we make a Higgs only once every 3 hours. The very definition of “needle in a haystack!”

Who made this discovery?

Two very large teams of physicists, and a whole bunch of people running the LHC accelerator at CERN. The two teams are the two experiments: ATLAS and CMS. I and my colleagues at UW are on ATLAS. If you hear someone say “I discovered the Higgs” they are using the royal-I. This is big science. Heck – the detector is half a (American) football field long, and about 8 or 9 stories tall and wide. This is the sort of work that is done by lots of people and countries working together. ATLAS currently has people from 38 countries – the USA being one of them.

What does a Cocktail Party have to do with it?

The cocktail party analogy is the answer to why some fundamental particles are more massive than particles (sadly, not why I have to keep letting my belt out year-after-year).

This is a cartoon of a cocktail party. Someone very famous has just entered the room. Note how everyone has clumped around them! If they are trying to get to the other side of the room, they are just not going to get there very fast!!

Now, lets say I enter the room. I don’t know that many people, so while some friends will come up and talk to me, it will be nothing like that famous person. So I will be able to get across the room very quickly.

The fact that I can move quickly because I interact with few people means I have little mass. The famous person has lots of interactions and can’t move quickly – and in this analogy they have lots of mass.

Ok. Bringing it back to the Higgs. The party and the people – that is the Higgs field. How much a particle interacts with the Higgs field determines its mass. The more it interacts, the more mass is “generated.”

And that is the analogy. You’ve been reading a long time. Isn’t this making you thirsty? Go get a drink!

Really, is this that big a deal?

Yes. This is a huge piece of the puzzle. This work is definitely worth a Nobel prize – look for them to award one to the people that first proposed it in 1960 (there are 6 of them, one has passed away – no idea how the committee will sort out the max of 3 they can give it to). We have confirmed a major piece of how nature works. In fact, this was the one particle that the Standard Model predicted that we hadn’t found. We’d gotten all the rest! We now have a complete picture of the Standard Model is it is time to start work on extending the Standard Model. For example, dark matter and dark energy are not yet in the Standard Model. We have no figured out how to fully unify everything we know about.

No. The economy won’t see an up-tick or a down-tick because of this. This is pure research – we do it to understand how nature and the universe around us works. There are sometimes, by-luck, spin-offs. And there are people that work with us who take it on as one of their tasks to find spin offs. But that isn’t the reason we do this.

What is next?

Ok. You had to ask that. So… First, we are sure we have found a new boson, but the real world – and data, is a bit messy. We have looked for it, and expect it to appear in several different places. It appeared in most of them – one place it seems to be playing hide and seek (where the Higgs decays to tau’s – a tau is very much like a heavy electron). Now, only one of the two experiments has presented results in the tau’s (CMS), so we have to wait for my experiment, ATLAS, to present its results before we get worried.

Second, and this is what we’d be doing no matter what happened to the tau’s, is… HEY! We have a shiny new particle! We are going to spend some years looking at it from every single angle possible, taking it out for a test drive, you know – kicking the tires. There is actually a scientific point to doing that – there are other possible theories out there that predict the existence of a Higgs that looks exactly like the Standard Model Higgs except for some subtle differences. So we will be looking at this new Higgs every-which way to see if we can see any of those subtle differences.

ATLAS and CMS also do a huge amount of other types of physics – none of which we are talking about right now – and we will continue working on those as well.

The European Organization for Nuclear Research, or CERN, the organization that built the LHC, announced Thursday that a transformer that helps cool part of the collider had malfunctioned, forcing operations to be suspended.

Think about that for a minute. CNET – a tech web publication – is following the ups and downs of the LHC. Have we ever had that level of interest in a HEP experiment before!? Not that I’m aware of. I remember the Fermilab start-up and even then no one tracked it like this.

One thing about the article:

No word on why it took CERN so long to let us know about the malfunction, though.

I don’t know for sure, but I can guess: they aren’t used to this level of press interest. So telling the press exactly what is going on with the machine gets done after everything else is taken care of (how to fix, implement the plan, etc.).

I wonder if they will have the latest magnet quench web page? We should write a desktop widget which has LHC status. 🙂

The space agency wanted to make sure its long-awaited and astronomically expensive telescope — soon to be launched into orbit above the turbulent fog of the atmosphere — made an appropriately cosmic splash. The advice from those of us in the press peanut gallery was always the same and simple: pictures — cosmic postcards like the live pictures of other planets being transmitted from the Viking and Voyager spacecraft — early and often.

This is PR 101 — everyone, including us scientists, is easily captured by pictures. Especially stunning ones. Sure — they may not be the best way to convey accurate scientific measurements – but they are very easy to relate to. Are we doing the right thing for the start of the LHC? Do we know what pictures – science pictures – we are going to be pushing to the public?

ATLAS has a whole outreach group (as does CMS, I’m sure). We have the ATLAS Book. We have a movie. But what cool picture are we going to give the press when the science starts? Another picture of our detector – like the one attached to this blog posting? Surely we can do better. Our event displays – most are tuned for us to look at as scientists, not for the press or the public. Do we have anything?

Enough of my ideas. What should we have ready when science starts to roll out? At the Tevatron we write these plain-English-summaries. They aren’t totally plain, unfortunately. But perhaps we should get someone from the PR office to work with every analysis that is published to work on something like that?

I’ve not said much (or here) about the lawsuit that seeks to halt the turn-on of the LHC because it may produce a mini-blackhole or other object that devours our earth and the universe. In response to the press when the original suit was filed, CERN sponsored a safety review, which was recently released.

The report’s conclusion is that, if the LHC were capable of destroying the earth, nature would have beaten us to the punch.

Read the report. It takes 96 pages to arrive at that pithy sentence. 🙂 Or read the Ars bit which is a good summary. They end with:

Overall, it’s hard to read this report and not wind up viewing the apocalyptic fears as simply being poorly thought through. It was striking how clearly the worries over the LHC have parallels to the fears over biotechnology, which came up during our recent interview with Carl Zimmer. There too, billions of years of natural experiments and decades’ worth of scientific experiment should be informing our view of safety; for at least some segment of the public, that’s not happening.

There is an essay by Dennis Overbye in the NYTimes today that is a much better discussion of the black hole flap that occurred a week ago, generated by a real article by Dennis. My favorite (laugh) quote:

Besides, the random nature of quantum physics means that there is always a minuscule, but nonzero, chance of anything occurring, including that the new collider could spit out man-eating dragons.

And my favorite serious quote:

“As in all explorations of uncharted domains, there may be a risk,” Dr. Rees wrote, “but there is a hidden cost of saying no.”

Definitely worth a read – much more so that the actual article itself, I think.

I really didn’t want to say something about this article. Actually, at first I wondered if it was just an excuse to show a truly awesome picture I wasn’t going to write anything. But then it started showing up on tech blogs, it rose to near the top of the New York Time’s most emailed articles. And non-physics friends of mine started asking what I thought about it. And then I saw some of the comments left on the article at the Herald Tribune’s version of the article (read them – it is worth it). I agree with Peter Woit: “it’s unclear why the story deserves any attention” However, I can hold out only so long.

Here is what I think: this article has the legs for reasons similar to why ID and Creationists are able to push the “evolution is only a theory” so effectively.

If you don’t have time to read the article: Wagner (ex physics researcher, lives in Hawaii) and Sancho (author, researcher on time theory (!?), lives somewhere in Spain) are suing Fermilab, the Department of Energy, and CERN to prevent the LHC from being turned on. Their’s is a doomsday worry: a small black hole or something similar will be created in the center of one of the detectors and will quickly expand to eat up the whole universe. Including us. I actually think that I’ve seen Wagner. One day, when I was a graduate student at Fermilab, I remember seeing a collection of people protesting outside the Batavia gate. I didn’t stop, but some friends did. It was someone from Hawaii who was worried we were going to end the universe. I don’t remember the name, but I suspect it was Wagner.

Now, in the evolution and creationism debate we scientist types call evolution a theory. In science it doesn’t get much more iron clad than that – pretty much the top of the heap. Note that we very carefully do not call it a fact. The reason is that science is always looking to improve the answers. We may have a model that fits all of our observations – but that isn’t to say that we’ve not missed something thus will need to extend the model or theory at a later time to account for new observations. Scientists are very careful about declaring the limits of their knowledge, and are very reluctant to go out on a limb and make a statement for which they do not have supporting evidence. That is part of the reason why we don’t call evolution a fact.

Now, lets go back to the article. There are lots of papers talking about mini-black holes and their possible production at the LHC. So far no one has seen any evidence of a black hole generated at any of the operating accelerators. But can you get any scientist to declare: “Absolutely, under no circumstances, ever will there be a black hold like this produced.”? I doubt it. If you asked a particle physicsts if they were worried about it – I don’t know of any that would be. Most would love to be at CERN, in fact, when the LHC starts up. I’d love to be there, but I may be teaching instead.

There is another aspect in this – risk evaluation. For example, it is much more dangerous to drive in your car than fly in an airplane. That is the raw science (statistics, whatever) of it. Yet we fear flying. When it comes to something like this how do you evaluate the risk? There is no way a non-scientist can do it themselves. The more science literacy there is the better people will understand the language that scientists use, but… And there is no way you would want to limit scientific endeavors and research to the list of topics that the non-scientist can easily understand! Ahhh… outreach!

Obligatory joke: fear not; us particle physicists will be first to pay if we’re wrong. 😉

But you have to admit — that is one amazing picture of CMS! These large detectors are stunning. I think someone should gather up the copyrights for some of these pictures and make a lulu.com book or something like that.

Unfortunately for Dr. Aymar, it is Dr. Heuer who will reap the reward, for after a decade and a half in the wilderness since the United States abandoned its own plans for a giant accelerator, called the superconducting super-collider, the subject of particle physics is just about to get sexy again.

Besides the implied total write-off of the Tevatron (grrr!), cool! Glad to see that the Economist gets it. Earlier on in the article it points out why things are about to get sexy again:

Inside it, he and the thousands of other physicists who work at CERN hope to find the secrets of the universe: dark matter, dark energy, extra dimensions, tiny black holes that evaporate in an eye-blink and the origins of mass itself.

This article was written because Dr. Heuer is about to take over from Dr. Aymar as the head of CERN (a big deal, obviously). And the article was pointing out that Aymar has worked hard to make the LHC come in on time and on budget (well, sort of), but will not be director any longer when the machine turns on and starts producing physics. Bad luck, eh?

Okay, humor me for a moment while I learn something: is this laughable because it suggests there are many “types” of higgs particles (which I’ve only ever seen reference to in this article) or just because the article suggests that the search is over and then quietly notes that we’re really still in the same place we were before the article was printed?

The latter. There have been discussions of the possibility of many Higgs for years — for longer than I’ve been in particle physics (>20 years – yikes! That is scary!).

How many Higgs particles depends on which world you live in. Lets say you live in the plain old Standard Model, and only the Standard Model. In that case, there is just one, the ONE Higgs. At the moment the Standard Model predicts pretty much every result we can measure. The Higgs particle was added to the original version of the Standard Model in order to get the W and Z boson masses correct — those are things we can measure today (unlike the Higgs, of course, which remains unseen).

Actually, that paragraph contains a lie — the Standard Model can’t explain everything — dark matter and dark energy, for example. There are other reasons why we think the Standard Model isn’t the whole story as well – so we have to fix it. So, on the one hand, we know it isn’t complete, but on the other hand we also know it can predict the results we measure at current experiments to amazing levels of accuracy. So, if we do fix it, we have to be careful of not breaking it in the process.

So we “extend” it. We develop new theories that “contain” the Standard Model. There are lots and lots of these theories. One of the more popular ones is called SUSY. Another is extra-dimensions. And there are more. Some of these models, like SUSY, actually contain 5 Higgs-like particles. The one that CP proposed in the paper referenced by this article also has 5 Higgs. In these extensions, btw, they must still get the W and Z masses correct – as the Standard Model does — and that is what Marcella (I think!) is complaining about: You might find another Higgs like particle, but the one in this model that does the work of the Higgs that gets the masses of the fermions and bosons like the W and Z right is still going to be just as hard to find.

On the other hand, finding a light Higgs as suggested would be a revelation. And grounds for a Nobel prize if the theory was born out. So the article that CP wrote is just fine. I was complaining about the way the press wrote it up.